With regard to the death of cells and tissues, apoptosis (active death of cells which is programmed in genes) has been drawing attention in recent years. Different from necrosis which is a pathological cell death, the apoptosis is considered to be the death incorporated from the first in the gene of the cell itself. That is, some external or internal factor triggers to activate the genes which program apoptosis, and apoptotic proteins biosynthesized by these genes or activation of existing apoptotic proteins cause active degeneration of the cells per se, thus resulting in cell death.